Abstract
We explore a number of novel effects near the orbital-order phase transition in a half-doped manganite, Pr0.5Ca0.5MnO3. To probe the unusual short-range orbital order in this system, we have performed coherent soft x-ray resonant scattering measurements in a Bragg geometry to measure dynamics. Near the transition temperature, we observe a small fluctuating component in the scattered signal that is correlated with three effects: a rapidly decreasing total signal and orbital domain size, as well as an abrupt onset of a broad background intensity that we attribute to the thermal production of correlated polarons. Our speckle results suggest that the transition is characterized by a competition between a pinned orbital domain topology that remains static and mobile domain boundaries that exhibit slow, temporal fluctuations.
Highlights
In transition metal oxides, such as cuprates, nickelates and cobaltates, spin and charge order are intimately coupled
Experiments performed on a range of cubic manganites suggest that orbital order (OO) is short-ranged compared to magnetic and charge order [11,12], yet the origins of this short range order remain unclear
Strain fields [13], doping heterogeneity [14], and intrinsic structural defects [15] could all play a critical role in determining the short correlation length and orbital ordering dynamics near the phase transition
Summary
In transition metal oxides, such as cuprates, nickelates and cobaltates, spin and charge order are intimately coupled. In the half-doped manganites, three ordered phases – charge, orbital and magnetic - are coupled. Strain fields [13], doping heterogeneity [14], and intrinsic structural defects [15] could all play a critical role in determining the short correlation length and orbital ordering dynamics near the phase transition.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
